There are several references to the Rydberg family in the book, "Gladys & Dinton Through the Years", available at the Alberta Histories Site here:
Indicates that Roy Rydberg paid the ultimate sacrifice in WW1; the Rydberg children attended the Glenview School in the period around 1910; in an article submitted by Irene Rydberg Tiegen, it indicates that Emil was born in Sweden and came to Iowa when he was 16, and had two sons, Roy and Ray; his wife died when the boys were 10 and 11.
Moved to Dinton District in 1904 and homesteaded NW 2, 21-26-W4. Married Caroline Beck, and had six daughters and one son: Selma married Charles E. Cote, and lived in Corseland until she passed away in 1952; Mary married Charles E. Cote and is postmistress at Corseland; Jean married Elven Tiegen and farmed at Dinton on the home place; Iris is in Deerholme Hospital at Lacombe; George taught school for several years, then trained as a weather forecaster in Vancouver and then worked in the Yukon among other places; Emil died in 1947; Caroline in 1960.
There is also a picture in which Caroline, Selma and Annie Rydberg are included.
The 1900 Census indicates that they were in Levey Township, Sac County, Iowa as follows:
Rydberg, Emil, Head, b. June 1871, age 29, married 1 year, b. Sweden, parents b. Sweden, emigrated 1890, naturalized, farmer
Rydberg, Alma, Wife, b. Sept. 1873, age 26, married 1 year, one child born, one child living, b. Sweden, parents b. Sweden, emigrated 1894,
Rydberg, Joseph W, Son, b. Sept. 1899, age 8 months, single, b. Iowa, parents b. Sweden
If this is the same Emil, then where are Roy and Ray???
Also, in Malvern Township, Mills County, Iowa,
Rydberg, Selma, Servant, b. March 1877, age 23, single, b. Sweden, parents b. Sweden, emigrated 1882
Also in Fairfield Township, Jefferson County:
Rydberg, Charles, Boarder, b. January 1880, age 20, single, b. Sweden, parents b. Sweden, emigrated 1887, R.R. laborer
This may clear up the mystery:
1900 Twin Groves Township, Jasper County, Missouri:
(this image is of poor quality right where the entry is)
Rydberg, Emil, Head, b. Aug. 1866(?), age 34(?), b. Sweden, father b. Germany, mother b. Sweden, emigrated 1881, drilling
Rydberg, Jennie B., Wife, b. Aug 187?, age ???, b. Missouri, father b. Missouri, mother b. Illinois
Rydberg, Roy W., Son, b. Jan ????, age ???, b. Nebraska, father b. Sweden, mother b. Missouri
Rydberg, Ray V., Son, b. May 1897, age 3, b. Iowa, father b. Sweden, mother b. Missouri
So, seems like there were two different Emil Rydbergs in Iowa at roughly the same time.
Hope this helps.